JP2006298642A - Ink jet recording device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To clean an ink jet head without moving the ink jet head and prevent a recording medium from being deformed and deviated while ensuring absorption force of the recording medium up to the ink jet head when absorbing the recording medium on a belt and feeding a paper sheet. <P>SOLUTION: A first ink jet head 2 and a second ink jet head 3 are arranged above a first conveyance part 4 and a second conveyance part 5, respectively, and a plurality of endless belts 6, 7 are arranged in the first and second conveyance parts 4, 5 at an interval, respectively. An auxiliary conveyance belt 18 is arranged between the endless belts 6 on the upstream side of the first ink jet head 2 where absorption force of the recording medium is reduced due to a clearance between the endless belts 6. They are simultaneously charged by a belt charging device 20 to supplement absorption force of the clearance of the endless belts 6 and ensure absorption force of the recording medium. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to an ink jet recording apparatus that discharges ink droplets onto a recording medium to draw predetermined characters and images.

The demand for high-speed recording is also increasing for inkjet recording devices that have the advantages of energy saving, quietness, and high image quality compared to the electrophotographic system, and a long inkjet head is fixed to the main body parallel to the paper width direction, and only the paper is conveyed. Thus, a line head type ink jet recording apparatus for recording is proposed.
In the ink jet head of an ink jet recording apparatus, the ink solvent evaporates from the nozzle from which the ink droplets are ejected and the ink in the nozzle is solidified, or foreign matter enters the nozzle and causes the nozzle to enter. Clogging may occur and the performance of ejecting ink droplets from the nozzles may be reduced.

Therefore, the ink jet recording apparatus includes a cleaning unit that recovers the lowered ejection performance, and is configured to maintain good recording quality. In the above-described line head type ink jet recording apparatus, conventionally, a flat belt that is slightly wider than the width of the recording medium is used as the conveying belt that adsorbs and conveys the recording medium. For this reason, a technique for recovering the ejection performance of an inkjet head by rotating the inkjet head to a non-recording area, which is an area where the nozzle does not face the recording medium and the conveyor belt, on a plane parallel to the recording medium is known. (For example, refer to Patent Document 1).
JP 2002-103638 A

  However, in the conventional example described in the above-mentioned Patent Document 1, since a large-sized inkjet head is rotated, ink droplet leakage, an increase in the movement time of the inkjet head, an increase in size of the apparatus, or positioning accuracy can be achieved. Various problems such as reproducibility occur. In order to avoid such a problem, it is conceivable to perform the cleaning process without moving the inkjet head.

  In this case, for example, in order to secure the arrangement position of the cleaning unit on the opposite surface of the inkjet head, the conveyance belt of the portion facing the inkjet head is divided, and these are separated in the direction intersecting the conveyance direction. It needs to be opened and placed. As described above, when the conveyance belt is divided and disposed at an interval, the recording medium adsorption force at the adsorption start position where the recording medium is placed on the supply side of the recording medium becomes smaller than before the division, and the recording medium At the start of the suction, the suction position varies in the transport direction, the recording medium moves in the transport direction relative to the transport belt, or the recording medium tilts. That is, there is an unsolved problem that the landing position of the ink droplets ejected from the nozzles of the ink jet head may be shifted to deteriorate the recording image quality.

  The present invention has been made paying attention to the above-described unsolved problems of the conventional example, and is an ink jet recording apparatus capable of reliably adsorbing and transporting the recording medium at least at the adsorption start position of the recording medium Is intended to provide.

  In order to solve the above-mentioned problem, the first invention according to the present invention is arranged at least on the recording medium supply side with a plurality of endless belts arranged at intervals in a direction intersecting with the conveyance direction of the recording medium, A transport unit that attracts and transports the recording medium to the outer peripheral surface of the endless belt, an inkjet head that discharges ink droplets to the recording medium transported by the transport unit, and at least the inkjet head of the transport unit An inkjet recording apparatus comprising an auxiliary conveyance belt disposed between a plurality of the endless belts at an adsorption start position of the recording medium on the upstream side in the conveyance direction.

According to the above configuration, when a plurality of endless belts are arranged at intervals, the auxiliary transport belt is arranged between the plurality of endless belts at least at the upstream side of the inkjet head in the transport direction and at the recording medium suction start position. By providing, a gap between a plurality of endless belts can be complemented, and the recording medium can be reliably adsorbed and conveyed.
Further, in a second invention according to the first invention, the conveying unit has a configuration in which a plurality of endless belts are wound between a pair of rollers provided on a recording medium supply side and a recording medium discharge side, The auxiliary conveyance belt is wound around a roller on the recording medium supply side and an auxiliary roller disposed between the roller and a roller on the recording medium discharge side. A recording device is provided.

According to the above configuration, since the auxiliary conveyance belt is wound around the recording medium supply side roller around which the plurality of endless belts are wound, the auxiliary conveyance belt rotates in synchronization with the plurality of endless belts. Adsorption of the medium is ensured.
Further, according to a third aspect, in the first aspect, the transport unit includes a plurality of supply-side endless belts arranged on the recording medium supply side at intervals in a direction intersecting the transport direction of the recording medium, A plurality of discharge-side endless belts connected to the supply-side endless belt and disposed on the recording medium discharge side so as not to overlap with the supply-side endless belt in the conveyance direction, Provided is an ink jet recording apparatus comprising a recording medium supply side extension of a discharge side endless belt.

According to the above configuration, since the plurality of discharge-side endless belts also serve as the auxiliary conveyance belt, it is not necessary to separately provide the auxiliary conveyance belt, and the supply-side endless belt and the discharge-side endless belt do not overlap in the conveyance direction. Therefore, by providing the nozzles of the ink jet head individually at the position between both belts, the entire area in the direction intersecting the recording medium conveyance direction can be set as the recording area.
According to a fourth aspect of the present invention, in any one of the first to third aspects, a charging unit is disposed in the direction crossing the recording medium conveyance direction in the vicinity of the conveyance unit, and electrostatic charging by charging is performed. An ink jet recording apparatus is provided that conveys a recording medium.

According to the above configuration, the recording medium can be reliably transported without deviation due to the electrostatic adsorption action by the charging means by charging the endless belt of the transport unit and the auxiliary transport belt.
According to a fifth invention, in any one of the first to fourth inventions, the auxiliary conveying belt has a recording medium attracting force at least at a position where it is separated from the recording medium, and a recording medium at a corresponding position of the endless belt. Provided is an ink jet recording apparatus which is set to be smaller than an attractive force.

According to the above configuration, the recording medium attracting force at the position where the auxiliary conveying belt is separated from the recording medium is smaller than the endless belt, so that the recording medium is smoothly separated from the auxiliary conveying belt, and the recording medium is deformed, displaced, etc. Can be prevented.
According to a sixth aspect of the present invention based on the fifth aspect, the auxiliary transport belt is configured such that the volume resistivity is set lower than the volume resistivity of the endless belt, and the recording medium adsorption force at a position where the auxiliary conveyance belt is separated from the recording medium is Provided is an ink jet recording apparatus characterized by being lowered from an endless belt.

According to the above configuration, the recording medium adsorption force of the auxiliary conveyance belt at the position where the auxiliary conveyance belt is separated from the recording medium is reduced from that of the endless belt, so that the separation of the recording medium from the auxiliary conveyance belt becomes smooth, and the deformation of the recording medium It is possible to prevent conveyance failure such as displacement.
According to a seventh aspect, in the fifth aspect, the width of the auxiliary conveying belt is set to be narrower than the width of the endless belt, and the recording medium adsorbing force at a position separated from the recording medium is reduced from that of the endless belt. An ink jet recording apparatus is provided.

According to the above configuration, the recording medium adsorption force of the auxiliary conveyance belt at the position where the auxiliary conveyance belt is separated from the recording medium is reduced from that of the endless belt, so that the separation of the recording medium from the auxiliary conveyance belt becomes smooth, and the deformation of the recording medium It is possible to prevent conveyance failure such as displacement.
According to an eighth aspect of the invention, there is provided the ink jet recording apparatus according to the fifth aspect of the invention, wherein the auxiliary conveying belt has a volume resistivity lower than that of the endless belt and a narrow belt width. I will provide a.

According to the above configuration, the recording medium adsorption force of the auxiliary conveyance belt at the position where the auxiliary conveyance belt is separated from the recording medium is reduced from that of the endless belt, so that the separation of the recording medium from the auxiliary conveyance belt becomes smooth, and the deformation of the recording medium It is possible to prevent conveyance failure such as displacement.
According to a ninth aspect of the present invention, in the fourth aspect of the present invention, the endless belt and the auxiliary transport belt are individually provided with charging means, and the amount of charging by the charging means of the auxiliary transport belt depends on the charging means of the endless belt. Provided is an ink jet recording apparatus characterized in that it is set so as to be less than a charge amount.

According to the above configuration, since the charging amount of the auxiliary conveying belt by the charging unit is smaller than the charging amount of the endless belt charging unit, the recording medium is smoothly separated from the auxiliary conveying belt, and the recording medium is deformed, displaced, etc. Can be prevented.
According to a tenth aspect of the present invention, in any one of the first to ninth aspects, the nozzle for ejecting ink droplets of the ink jet head is disposed between the plurality of endless belts, and the plurality of endless portions of the transport unit are disposed. Provided is an ink jet recording apparatus characterized in that a cleaning section for cleaning the ink jet head is disposed at a position facing the ink jet head between belts.

According to the above configuration, since the cleaning unit for cleaning the inkjet head is disposed at a position facing the inkjet head, the inkjet head can be cleaned without moving the inkjet head.
The eleventh aspect of the invention is that, in the third aspect of the invention, nozzles for discharging ink droplets of the supply side and discharge side inkjet heads are disposed between the supply side endless belts and between the discharge side endless belts, respectively. A supply-side and discharge-side cleaning unit for cleaning the nozzle is disposed between the supply-side endless belt and the discharge-side endless belt so as to be movable forward and backward with respect to the nozzle. The discharge-side recording medium conveyance path connected to the supply-side endless belt, and the suction-side recording medium conveyance path to the suction start position between the supply-side endless belt through the lower side of the supply-side cleaning unit. And an auxiliary belt conveyance path that forms an auxiliary conveyance belt.

  According to the above configuration, since the inkjet head and the cleaning unit are disposed between the supply-side endless belt and the discharge-side endless belt, respectively, the entire region in the direction intersecting the recording medium conveyance direction can be set as a recording region. In addition, the inkjet head can be cleaned without moving the inkjet head, and the discharge-side endless belt is passed through the lower side of the supply-side cleaning unit to prevent interference with the cleaning unit and to the recording medium supply side. It can be extended to function as an auxiliary transport belt.

  According to a twelfth aspect, in the eleventh aspect, first and second charging means are individually provided on the discharge side recording medium conveyance path and the auxiliary belt conveyance path on the discharge side endless belt. The first and second belt charging amounts when passing through the second charging unit are smaller than the belt charging amount when passing through the first charging unit and the belt charging amount of the supply-side endless belt. An ink jet recording apparatus characterized in that the charge amount of the charging means is set.

  According to the above configuration, the optimum suction force can be set on each of the recording medium supply side and the recording medium discharge side with respect to the discharge-side endless belt, thereby conveying the deformation, displacement, etc. of the recording medium. Defects can be prevented.

Hereinafter, a first embodiment of an ink jet recording apparatus of the present invention will be described with reference to the drawings.
FIG. 1 is a schematic configuration diagram of an ink jet recording apparatus according to the present embodiment, FIG. 2A is a plan view thereof, and FIG. 2B is a front view thereof. In FIG. 1, a recording medium 1 is conveyed from the upper right to the lower left in the figure in the direction of the arrow in the figure, printed in a printing area in the middle of the conveyance, and then discharged. This type is called a line head type ink jet recording apparatus. The ink jet head of this embodiment is arranged not only at one place but also at two places.

  Reference numeral 2 in the figure denotes a first inkjet head provided on the upstream side in the transport direction of the recording medium 1, and reference numeral 3 denotes a second inkjet head also provided on the downstream side, below the first inkjet head 2. Is provided with a first transport unit 4 for transporting the recording medium 1, and a second transport unit 5 is provided below the second inkjet head 3. The first transport unit 4 is composed of four first endless belts 6 arranged at a predetermined interval in a direction intersecting the transport direction of the recording medium 1, and the second transport unit 5 is also a recording medium. It is composed of four second endless belts 7 arranged at predetermined intervals in a direction intersecting with one conveyance direction.

  The four second endless belts 7 as well as the four first endless belts 6 are alternately arranged adjacent to each other. A driving roller 8 is disposed at the connecting portion of the first endless belt 6 and the second endless belt 7, a driven roller 9 is disposed on the upstream side, and a driven roller 10 is disposed on the downstream side. . The first endless belt 6 is wound around the driving roller 8 and the driven roller 9, the second endless belt 7 is wound around the driving roller 8 and the driven roller 10, and an electric motor 11 is connected to the driving roller 8. Yes. Accordingly, when the driving roller 8 is rotationally driven by the electric motor 11, the first transport unit 4 configured by the first endless belt 6 and the second transport unit 5 configured by the second endless belt 7 are synchronized with each other and Moved at the same speed.

  The first inkjet head 2 and the second inkjet head 3 are, for example, for each of six colors of yellow (Y), magenta (M), cyan (C), light magenta (Lm), light cyan (Lc), and black (K). In addition, nozzles (not shown) are arranged shifted in the conveyance direction of the recording medium 1. Ink is supplied to the inkjet heads 2 and 3 from ink tanks of respective colors (not shown) via ink supply tubes. Each inkjet head 2 and 3 has a plurality of nozzles formed in the direction intersecting with the conveyance direction of the recording medium 1 as described above. By doing so, minute ink dots are formed on the recording medium 1. By performing this for each color, it is possible to perform so-called one-pass full-color printing only by passing the recording medium 1 from the first transport unit 4 to the second transport unit 5 once. That is, the area where the inkjet heads 2 and 3 are disposed corresponds to the print area.

  As a method for discharging and outputting ink from each nozzle of the ink jet head, there are an electrostatic method, a piezo method, a film boiling ink jet method, and the like. In the electrostatic method, when a drive signal is given to the electrostatic gap that is an actuator, the diaphragm in the cavity is displaced to cause a pressure change in the cavity, and ink droplets are ejected and output from the nozzle by the pressure change. Is. In the piezo method, when a drive signal is given to the piezo element, which is an actuator, the diaphragm in the cavity is displaced, causing a pressure change in the cavity, and ink droplets are ejected from the nozzle by the pressure change. is there. In the film boiling ink jet method, there is a micro heater in the cavity, the ink is instantaneously heated to 300 ° C. or more, the ink is in a film boiling state, bubbles are generated, and ink droplets are ejected and output from the nozzles due to the pressure change. It is said that. The present invention can be applied to any ink output method.

  The nozzles of the first inkjet head 2 are formed between the four first endless belts 6 of the first conveying unit 4, and the nozzles of the second inkjet head 3 are the four second endless of the second conveying unit 5. It is formed between the belts 7. This is because the inkjet heads 2 and 3 are cleaned by a cleaning unit, which will be described later, but one-pass printing cannot be performed with only one of the inkjet heads. For this reason, the first ink jet head 2 and the second ink jet head 3 are arranged so as to be shifted in the transport direction of the recording medium 1 as described above in order to compensate for the portions that cannot be printed with each other.

  Disposed below the first inkjet head 2 is the first cleaning cap 12 for cleaning the first inkjet head 2, and disposed below the second inkjet head 3 is the second inkjet head. 2 is a second cleaning cap 13 that cleans 3. Each of the cleaning caps 12 and 13 is sized so as to pass between the four first endless belts 6 of the first transport unit 4 and between the four second endless belts 7 of the second transport unit 5. It is formed.

  An upstream side of the driven roller 9 is provided with two pairs of gate rollers 14 for adjusting the feeding timing of the recording medium 1 supplied from a sheet feeding unit (not shown) and correcting the skew of the recording medium 1. Yes. The skew is a change in the attitude of the recording medium 1 with respect to the transport direction. Further, a spur 15 and a paper discharge roller 16 for discharging the recording medium 1 from the print area are disposed on the downstream side of the driven roller 10.

  On the other hand, an auxiliary roller 17 is disposed on the downstream side in the transport direction of the recording medium 1 with respect to the driven roller 9 and on the upstream side in the transport direction of the recording medium 1 near the first cleaning cap 12. Four auxiliary conveyance belts 18 are wound around the belt 9. The auxiliary conveying belt 18 is disposed between the four first endless belts 6 and just fills the gap. The auxiliary conveying belt 18 and the first endless belt 6 have the same or almost the same conveying surface of the recording medium.

  A belt charging device 19 is disposed downstream of the drive roller 8 in the conveyance direction of the recording medium 1 so as to face the lower second endless belt 7 from below in a direction intersecting the conveyance direction of the recording medium 1. Has been. Further, a belt charging device 20 is disposed in the same direction as described above so as to face the driven roller 9 with the first endless belt 6 and the auxiliary conveyance belt 18 interposed therebetween. These belt charging devices 19 and 20 are constituted by a discharging device such as a corotron, for example, and charge the first endless belt 6, the second endless belt 7, and the auxiliary conveyance belt 18, respectively.

  In general, these belts are composed of a medium / high resistance body or an insulator, and when charged by a belt charging device, the charge applied to the surface is also composed of a high resistance body or an insulator. The recording medium 1 is caused to generate dielectric polarization, and the recording medium 1 can be adsorbed (electrostatic adsorption) to the belt by an electrostatic force generated between the charge generated by the dielectric polarization and the charge on the belt surface. The charging unit may be a charging roller to which a constant voltage is applied, for example.

  Then, a pressing roller 21 that presses the recording medium 1 against both the belts 6 and 18 with the first endless belt 6 and the auxiliary conveyance belt 18 sandwiched between the driven rollers 9 is rolled as shown in FIG. In addition, a pressing roller 22 that presses the recording medium 1 against the second endless belt 7 with the first endless belt 6 and the second endless belt 7 sandwiched between the driving rollers 8 is shown by a one-dot chain line in FIG. Has been transferred to.

  Therefore, according to this ink jet recording apparatus, when the driving roller 8 is rotationally driven by the electric motor 11 in this state, the rotational driving force is transmitted to the driven roller 9 via the first endless belt 6. Since the auxiliary conveyance belt 18 is wound around the driven roller 9 together with the first endless belt 6, the first endless belt 6 and the auxiliary conveyance belt 18 are synchronized with each other and moved at the same speed.

  In this state, the belt charging device 20 charges the surfaces of the first endless belt 6 and the auxiliary conveyance belt 18 of the first conveyance unit 4. In this state, the recording medium 1 is fed from the gate roller 14, and the pressing roller 21 When the recording medium 1 is pressed against the first endless belt 6 and the auxiliary conveyance belt 18, the recording medium 1 is attracted to the surfaces of the first endless belt 6 and the auxiliary conveyance belt 18 by the action of the dielectric polarization described above.

As described above, the recording medium 1 is simultaneously attracted to the first endless belt 6 and the auxiliary conveying belt 18 at the suction start position in the vicinity of the position immediately above the driven roller 9, so that the entire recording medium 1 is compared with the first endless belt 6 alone. Since the adsorbing force increases, it is more reliably adsorbed.
The accuracy of the suction start position of the recording medium 1 is very important. When a positional shift or the like occurs, the relative position between the nozzle of the first inkjet head 2 and the recording medium 1 shifts, and the ink droplets discharged from the nozzles Since the landing position is deviated, the print quality is adversely affected. By providing the auxiliary conveyance belt 18, there is an effect of preventing the above problems.

  The recording medium 1 is moved below the first inkjet head 2 by moving the first endless belt 6 and the auxiliary conveyance belt 18 to the downstream side in the conveyance direction of the recording medium 1 with the recording medium 1 adsorbed in this manner. And printing is performed by ejecting ink droplets from the nozzles formed in the first inkjet head 2. When printing by the first ink jet head 2 is completed, the recording medium 1 is moved to the downstream side in the conveyance direction of the recording medium 1 and is transferred to the second endless belt 7 of the second conveyance unit 5. As described above, since the surface of the second endless belt 7 is also charged by the belt charging device 19, when the recording medium 1 is pressed against the second endless belt 7 by the pressing roller 22, recording is performed by the above-described action of dielectric polarization. The medium 1 is adsorbed on the surface of the second endless belt 7.

  The adsorbed recording medium 1 is moved below the second inkjet head 3 by the movement of the second endless belt 7 to the downstream side in the conveyance direction of the recording medium 1, and nozzles formed in the second inkjet head 3. Ink droplets are ejected from the ink and printing is performed. When printing by the second ink jet head 3 is completed, the recording medium 1 is further moved downstream in the conveyance direction of the recording medium 1, and the recording medium 1 is separated from the surface of the second endless belt 7 by a separation device (not shown). The spur 15 and the paper discharge roller 16 discharge the recording medium 1 to a paper discharge unit (not shown).

  When the first and second inkjet heads 2 and 3 need to be cleaned, the conveyance of the recording medium 1 is stopped, and the first and second inkjet heads 2 and 3 and the first and second cleaning caps 12 and 13 are stopped. The first and second cleaning caps 12 and 13 are raised with no recording medium 1 interposed therebetween. As a representative of these cleaning caps 12 and 13, the configuration of the first cleaning cap 12 for cleaning the first inkjet head 2 is shown in FIG.

  The first cleaning cap 12 covers a nozzle 52 formed on the nozzle surface 51 of the first inkjet head 2 and is disposed at the bottom of a rectangular bottomed cap body 53 that can be in close contact with the nozzle surface 51. The ink absorber 54, the tube 55 connected to the bottom of the cap body 53, and a lifting device (not shown) are connected to a negative pressure generating device such as a tube pump (not shown).

  The first cleaning cap 12 is raised by a lifting device (not shown), and the cap body 53 is brought into close contact with the nozzle surface 51 of the first inkjet head 2. In this state, when a negative pressure is generated in the cap body 53 by the negative pressure generating device, ink droplets and bubbles are sucked out from the nozzles 52 provided on the nozzle surface of the first inkjet head 2, and the first inkjet head. 2 is cleaned. When the cleaning is completed, the first cleaning cap 12 is lowered.

Since the configuration of the second cleaning cap 13 is the same as this, the description thereof is omitted. In some cases, the nozzle surface may be stroked with a wiper (not shown) to adjust the meniscus of each nozzle.
As described above, according to the ink jet recording apparatus of the present embodiment, the ink jet heads 2 and 3 can be cleaned without moving the first and second ink jet heads 2 and 3. Various problems caused by the movement can be avoided. Further, regarding the decrease in the suction force at the suction start position of the recording medium 1 generated by dividing the transport belt, the first transport unit 4 is configured on the upstream side of the first ink jet head 2 in the transport direction of the recording medium 1. The four auxiliary transport belts 18 are wound around the first endless belts 6 so as to fill the gaps between the four first endless belts 6 and the charged first endless belts 6 and the auxiliary transport belts. Since the recording medium 1 can be adsorbed on the surface of the recording medium 18, the gap between the four first endless belts 6 constituting the first transport unit 4 is complemented to supplement the adsorbing force. The recording medium 1 can be reliably sucked and transported at the suction start position 1.

As a result, it is possible to prevent the landing position deviation of the ink droplets ejected from the nozzles of the inkjet head and improve the recording image quality.
Next, a second embodiment of the ink jet recording apparatus of the present invention will be described with reference to FIGS. The basic structure of the ink jet recording apparatus of the present embodiment is substantially the same as that of the first embodiment shown in FIGS.

  A first inkjet head 2 and a second inkjet head 3 are arranged between the first endless belt 6 (supply-side endless belt) and a second endless belt 29 (discharge-side endless belt), respectively. First and second cleaning caps 12 and 13 (supply-side and discharge-side cleaning units) for cleaning the nozzles are respectively disposed at positions facing 2 and 3 so as to be movable up and down (movable back and forth).

In the present embodiment, the auxiliary conveyance belt 18 in the first embodiment described above is omitted, and instead, the second endless belt 29 of the second conveyance unit 5 is extended to the recording medium supply side, and this recording medium supply side extension. The auxiliary conveyance belt portion 29a is configured by the portion.
Specifically, the transport path of the second endless belt 29 is disposed on the lower right side of the driving roller 8 from the auxiliary roller 30 disposed on the lower left side of the driving roller 8 and on the driven roller 10. The discharge-side recording medium that forms the second transport unit 5 connected to the first endless belt 6 that is wound on the auxiliary roller 31 and passes through the lower side of the second cleaning cap 13 toward the first transport unit 4. The driven roller 9 is wound through the conveyance path 29b and the auxiliary roller 31 from the auxiliary roller 31 to the lower left of the driven roller 9, and is further provided below the auxiliary roller 17 via the auxiliary roller 17. The auxiliary belt 33 is formed by an auxiliary belt conveyance path 29c that forms an auxiliary conveyance belt portion 29a that passes through the lower side of the first cleaning cap 12 toward the auxiliary roller 30.

  5B, the first endless belt 6 is charged in the direction intersecting the conveyance direction of the recording medium 1 in the space surrounded by the driven roller 9 and the auxiliary rollers 32 and 33. A belt charging device 28 dedicated to one endless belt 6 is provided. Further, the second endless belt 29 has belt charging devices 19 and 23 that are individually charged by the discharge-side recording medium conveyance path 29b and the auxiliary belt conveyance path 29c. The belt charging device 19 is disposed so as to face the lower surface of the second endless belt 29 between the driving roller 8 and the auxiliary roller 30 (the side on the discharge side recording medium conveyance path), and the belt charging device 23 includes a driven roller. 9 and the auxiliary roller 32 is disposed so as to face the slope of the auxiliary conveying belt portion 29a (the auxiliary belt conveying path entering side).

  As described above, in the ink jet recording apparatus of the present embodiment as well, the first and second ink jet heads 2 and 3 are not moved and the ink jet heads 2 and 3 are not moved as in the case of the ink jet recording apparatus of the first embodiment. Since cleaning can be performed, various problems caused by moving the inkjet head can be avoided. Further, the entire area in the direction intersecting the conveyance direction of the recording medium can be set as the recording area.

  Then, on the upstream side of the first inkjet head 2 in the conveyance direction of the recording medium 1, the gaps between the four first endless belts 6 constituting the first conveyance unit 4 are filled, and the first endless belts 6 Since the four auxiliary transport belt portions 29a are wound between them, the recording medium 1 can be adsorbed on the charged first endless belt 6 and the surfaces of the auxiliary transport belt portions 29a. The gap portion of the four first endless belts 6 is complemented to supplement the suction force, and the recording medium 1 can be reliably sucked and transported at the suction start position of the recording medium 1.

Further, since the second endless belt 29 also serves as the auxiliary conveyance belt portion 29a, it is not necessary to newly provide an auxiliary conveyance belt. At this time, since the second endless belt 29 passes under the first cleaning cap 12, it does not interfere with the first cleaning cap 12 and does not affect its operation.
Next, a third embodiment of the ink jet recording apparatus of the present invention will be described with reference to FIGS. 6 (a) is a plan view, FIG. 6 (b) is a front view, and FIG. 7 is a schematic diagram of a CC section of FIG. 6 (b). The basic structure of the ink jet recording apparatus of the present embodiment is the same as that of the first embodiment shown in FIGS. 1 and 2, and the first and second for cleaning the first and second ink jet heads 2 and 3 are the same. The cleaning caps 12 and 13 are the same as those in FIG. 3 of the first embodiment. Further, the charging method and adsorption principle of the belt charging devices 19 and 20 are the same as those in the first embodiment.

In the present embodiment, the recording medium adsorption force (hereinafter referred to as adsorption force) of the auxiliary conveyance belt 18 at least at a position where the auxiliary conveyance belt 18 is separated from the recording medium 1 is made smaller than the adsorption force of the first endless belt 6. It is set. Specifically, the belt width 26 of the auxiliary conveyance belt 18 is made narrower than the belt width 27 of the first endless belt 6.
FIG. 7 shows that the recording medium 1 is adsorbed on the first endless belt 6 and the auxiliary conveying belt 18 at a position near the auxiliary roller 17 where the auxiliary conveying belt 18 is separated from the recording medium 1 (hereinafter referred to as a separating position). This is a comparative view showing the difference in the suction force Fs at the separation position of the recording medium 1 before and after the belt width 26 of the auxiliary transport belt 18 is narrowed. FIG. 7A shows a case where the belt width 26 of the auxiliary transport belt 18 of the present embodiment is narrower than the belt width 27 of the first endless belt 6. FIG. 7B shows the case of the auxiliary transport belt 18. The case where the belt width 26 is the same as the belt width 27 of the first endless belt 6 is shown.

  In the present embodiment, as shown in FIG. 7A, the belt width 26 of the auxiliary transport belt 18 is made narrower than the belt width 27 of the first endless belt, thereby reducing the suction area and the auxiliary transport belt 18 at the separation position. Is smaller than the suction force Fm of the first endless belt 6, the force that pulls the recording medium 1 downward when the auxiliary transport belt 18 is separated from the recording medium 1 is weakened. The recording medium 1 is separated from the auxiliary conveying belt 18 while maintaining a substantially flat surface without greatly affecting the suction force of the first endless belt 6 of the recording medium 1 and without being deformed from the auxiliary conveying belt 18. Since 1 does not slide on the first endless belt 6, it is possible to reliably prevent the occurrence of a transfer position shift.

  Incidentally, as shown in FIG. 7B, when the belt width 26 of the auxiliary conveying belt 18 and the belt width 27 of the first endless belt 6 are set to be the same, the recording medium 1 is auxiliary conveyed at the separation position. When the belt 18 is attracted to the downstream side of the auxiliary roller 17 by the suction force Fs, the surface of the recording medium 1 may be deformed in a undulating state. If the recording medium 1 is conveyed to the position of the first inkjet head 2 in this deformed state, The landing position of the ink droplets ejected from the nozzles is deviated from the normal position, the print quality is deteriorated, the recording medium 1 is not smoothly separated from the separation position, and the recording medium 1 is placed on the first endless belt 6. There is a possibility that the conveyance position of the recording medium 1 may be shifted due to sliding.

  In the third embodiment, the suction force Fs of the auxiliary transport belt 18 is set to be smaller than the suction force Fm of the first endless belt 6. However, in this example, the width of the auxiliary transport belt 18 is narrowed. Without being limited thereto, the volume resistivity of the auxiliary transport belt 18 is made lower than the volume resistivity of the first endless belt 6 while keeping the belt widths of the first endless belt 6 and the auxiliary transport belt 18 equal. May be.

According to this, by using a medium resistance member having a low volume resistivity (preferably less than 10 ¹² Ωcm) for the auxiliary conveying belt 18, the auxiliary conveying belt 18 and the first endless belt 6 are used by the common belt charging device 20. Are simultaneously charged, the charge decay rate of the auxiliary conveyance belt 18 having a low volume resistivity is larger than that of the first endless belt 6, and therefore, the charge amount of the auxiliary conveyance belt 18 at the separation position is 1 Less than the charge amount of the endless belt 6.

Therefore, the suction force Fs of the auxiliary conveyance belt 18 at the separation position is smaller than the suction force Fm of the first endless belt 6.
As a result, similarly to the above, the recording medium 1 is separated from the auxiliary transport belt 18 without being deformed, and is kept substantially flat, and the recording medium 1 does not slide on the first endless belt 6. Therefore, it is possible to reliably prevent the occurrence of the transfer position deviation.

  Furthermore, the configuration is not limited to this, and the configuration in which the width of the auxiliary conveyance belt 18 of the third embodiment is narrowed and the configuration in which the volume resistivity of the auxiliary conveyance belt 18 is lowered may be used in combination. According to this, by reducing the volume resistivity of the auxiliary transport belt 18, the adsorption force Fs of the auxiliary transport belt 18 shown in FIG. 7A can be further reduced. As a result, similarly to the above, the recording medium 1 is separated from the auxiliary transport belt 18 without being deformed, and is kept substantially flat, and the recording medium 1 does not slide on the first endless belt 6. Therefore, it is possible to reliably prevent the occurrence of the transfer position deviation.

Each of the configurations of the third embodiment has an advantage that a common charging unit can be used to give different charge amounts to the first endless belt 6 and the auxiliary conveyance belt 18, and the charging unit is provided separately. Compared to the case, the number of parts and the manufacturing cost can be reduced.
Next, a fourth embodiment of the ink jet recording apparatus of the present invention will be described with reference to FIG. FIG. 8 is a front view of the main part of the present embodiment.

  The basic structure of the ink jet recording apparatus according to this embodiment is the same as that of the first embodiment shown in FIGS. In this embodiment, a charging unit for the auxiliary conveyance belt 18 and a charging unit for the first endless belt 6 are provided separately. In FIG. 8, reference numeral 23 denotes a belt charging device as charging means for the auxiliary conveyance belt 18, and reference numeral 28 denotes a belt charging device as charging means for the first endless belt 6.

  The belt charging device 23 is disposed at a position facing the lower surface of the auxiliary conveyance belt 18 below the auxiliary roller 17 in a direction crossing the conveyance direction of the recording medium 1, and the belt charging device 28 is driven in the same direction as described above. It is disposed at a position facing the lower surface of the first endless belt 6 on the lower left side of the roller 9. The charging method and the adsorption principle of the charging device are the same as those in the first embodiment, and a description thereof will be omitted. Then, charging is performed so that the charging amount of the auxiliary conveyance belt 18 by the belt charging device 23 is smaller than the charging amount of the first endless belt 6 by the belt charging device 28.

  Thereby, the suction force of the auxiliary conveyance belt 18 at the separation position is smaller than the suction force of the first endless belt 6. As a result, as in the third embodiment, the recording medium 1 is separated from the auxiliary transport belt 18 without being deformed and maintained substantially flat, and the recording medium 1 slides on the first endless belt 6. As a result, it is possible to reliably prevent the occurrence of a shift in the transport position.

Next, a fifth embodiment of the ink jet recording apparatus of the present invention will be described with reference to FIGS. The basic structure of the ink jet recording apparatus of this embodiment is the same as that of the second embodiment. Here, the charging method and suction principle of the belt charging devices 28, 19, and 23 are the same as those in the first embodiment, and a description thereof will be omitted.
In the present embodiment, the belt charging amount is set such that the belt charging amount when the auxiliary conveying belt portion 29a passes through the belt charging device 23 is smaller than the charging amount when passing through the belt charging device 19 and the charging amount of the first endless belt 6. Charge amounts of the devices 23 and 19 are set.

  Here, the charged state of the second endless belt 29 (auxiliary transport belt portion 29a) will be described. First, when the belt charging device 23 passes, the belt charging device 23 charges a smaller amount than the charging amount of the belt charging device 28 to the first endless belt 6. Then, as the driven roller 9 and the auxiliary roller 17 are turned over and the recording medium 1 is moved downstream in the conveying direction, the charge amount is gradually attenuated, and the charge amount becomes the minimum before the belt charging device 19.

  Next, when the belt charging device 19 further moves and passes through the belt charging device 19, the belt charging device 19 is charged with a larger amount than when passing through the belt charging device 23, so that the charging amount is about the same as that of the first endless belt 6. Increase. Then, the charge amount is gradually attenuated while passing through the second transport unit 5 and passing through the driven roller 10 and the auxiliary rollers 31 and 32, and the charge amount becomes the minimum before the belt charging device 23. This is one cycle, and this charging state is repeated.

According to this, since the belt charge amount of the auxiliary conveyance belt portion 29a is smaller than the charge amount of the first endless belt 6, the recording medium 1 is deformed from the auxiliary conveyance belt 18 as in the third embodiment. Therefore, the recording medium 1 is not slid on the first endless belt 6, so that it is possible to reliably prevent the occurrence of a shift in the transport position.
Further, the charging amount of the second endless belt 29 constituting the second conveying unit 5 when passing through the belt charging device 19 is larger than the charging amount of the auxiliary conveying belt unit 29a when passing through the belt charging device 23, and the first endless belt 6. Therefore, the suction force of the second endless belt 29 in the second transport unit 5 is larger than the suction force of the auxiliary transport belt unit 29a and is about the same as that of the first endless belt 6. As a result, the recording medium 1 can be smoothly transported from the first transport unit to the second transport unit, and transport defects such as misalignment can be prevented.

  In the first to fifth embodiments, the example in which the electrostatic force is used as the force for attracting the recording medium onto the belt has been described. However, the present invention is not limited to this. For example, the spur is located above the belt. Needless to say, a so-called friction feed system in which a plurality of recording media are arranged and pressed against the belt surface to convey the recording media by a frictional force acting between the recording media and the belt can be used.

1 is a schematic configuration diagram showing a first embodiment of an ink jet recording apparatus of the present invention. Detailed explanatory drawing of FIG. 1, (a) is a top view, (b) is a front view. FIG. FIG. 6 is a schematic configuration diagram illustrating second and fifth embodiments of the ink jet recording apparatus of the present invention. 4 is a detailed explanatory view of FIG. 4, (a) is a plan view, (b) is a front view. The figure which shows 3rd Embodiment of the inkjet recording device of this invention, (a) is a top view, (b) is a front view. FIG. 6B is a schematic cross-sectional view taken along the line C-C in FIG. 6B, (a) is a belt width difference diagram, and (b) is a belt width same width diagram. The principal part front view which shows 4th Embodiment of the inkjet recording device of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Recording medium, 2 ... 1st inkjet head, 3 ... 2nd inkjet head, 4 ... 1st conveyance part, 5 ... 2nd conveyance part, 6 ... 1st endless belt, 7 ... 2nd endless belt, 8 ... Drive Roller, 9 ... driven roller, 10 ... driven roller, 11 ... electric motor, 12 ... first cleaning cap, 13 ... second cleaning cap, 14 ... gate roller, 15 ... spur, 16 ... paper discharge roller, 17 ... auxiliary roller , 18 ... auxiliary transport belt, 19 ... belt charging device, 20 ... belt charging device, 21 ... pressing roller, 22 ... pressing roller, 23 ... belt charging device, Fm ... first endless belt suction force, Fs ... auxiliary transport belt suction 26: Auxiliary conveyance belt width, 27: First endless belt width, 28 ... Belt charging device, 29 ... Second endless belt, 29a ... Auxiliary conveyance belt section, 29b ... Ejection side recording Body transport path 29c ... auxiliary belt transport path, 30 ... auxiliary roller, 31 ... auxiliary roller, 32 ... auxiliary roller, 33 ... auxiliary roller

Claims (12)

  At least on the recording medium supply side, a plurality of endless belts are disposed at intervals in a direction intersecting the recording medium conveyance direction, and a conveyance unit that adsorbs and conveys the recording medium to the outer peripheral surface of the endless belt; An inkjet head that discharges ink droplets to a recording medium conveyed by the conveyance unit, and at least a plurality of the adsorption positions at the upstream side of the conveyance unit upstream of the inkjet head in the conveyance direction. An ink jet recording apparatus comprising: an auxiliary conveying belt disposed between endless belts.   The conveyance unit has a configuration in which a plurality of endless belts are wound between a pair of rollers provided on a recording medium supply side and a recording medium discharge side, and the auxiliary conveyance belt includes a roller on the recording medium supply side 2. The ink jet recording apparatus according to claim 1, wherein the ink jet recording apparatus is wound between an auxiliary roller disposed between the roller and a recording medium discharge side roller.   The conveyance unit includes a plurality of supply-side endless belts arranged on the recording medium supply side at intervals in a direction intersecting the conveyance direction of the recording medium, connected to the supply-side endless belt, and supplied-side endless A plurality of discharge-side endless belts arranged on the recording medium discharge side so as not to overlap with the belt in the conveyance direction, and the auxiliary conveyance belt is configured by a recording medium supply side extension of the discharge-side endless belt. The inkjet recording apparatus according to claim 1, wherein:   4. The recording medium according to claim 1, wherein a charging unit is disposed in the vicinity of the transport unit in a direction intersecting with the transport direction of the recording medium, and the recording medium is transported by electrostatic attraction by charging. The ink jet recording apparatus described.   2. The auxiliary conveyance belt is set such that a recording medium adsorption force at least at a position where it is separated from the recording medium is smaller than a recording medium adsorption force at a corresponding position of the endless belt. The inkjet recording apparatus according to any one of 4.   6. The auxiliary conveying belt has a volume resistivity set lower than that of the endless belt, and a recording medium attracting force at a position where the auxiliary conveying belt is separated from the recording medium is lower than that of the endless belt. 2. An ink jet recording apparatus according to 1.   6. The inkjet according to claim 5, wherein a width of the auxiliary conveying belt is set to be narrower than a width of the endless belt, and a recording medium attracting force at a position where the auxiliary conveying belt is separated from the recording medium is reduced from that of the endless belt. Recording device.   6. The ink jet recording apparatus according to claim 5, wherein the auxiliary conveying belt is set to have a volume resistivity lower than that of the endless belt and a narrow width of the belt.   The endless belt and the auxiliary conveyance belt are individually provided with charging means, and the charging amount by the charging means of the auxiliary conveying belt is set to be smaller than the charging amount by the charging means of the endless belt. The ink jet recording apparatus according to claim 4.   A nozzle that discharges ink droplets of the inkjet head is disposed between a plurality of endless belts, and a cleaning unit that cleans the nozzles is disposed at a position facing the nozzles between the plurality of endless belts of the transport unit. The ink jet recording apparatus according to claim 1, wherein the ink jet recording apparatus is disposed so as to be movable forward and backward with respect to the nozzle.   Nozzles for discharging ink droplets of the supply-side and discharge-side inkjet heads are disposed between the supply-side endless belts and between the discharge-side endless belts, and the nozzles between the supply-side endless belt and the discharge-side endless belt. A supply-side and discharge-side cleaning unit that cleans the nozzle is disposed in a position opposite to the nozzle so as to be able to advance and retreat with respect to the nozzle, and the discharge path connected to the supply-side endless belt is connected to the discharge-side endless belt. A side recording medium conveyance path, and an auxiliary belt conveyance path that extends from the discharge side recording medium conveyance path through the lower side of the supply side cleaning unit to the suction start position between the supply side endless belts to form an auxiliary conveyance belt. The inkjet recording apparatus according to claim 3, wherein   First and second charging means are separately provided on the discharge-side endless belt on the discharge-side recording medium conveyance path and the auxiliary belt conveyance path, and the belt charge amount when passing through the second charging means is determined. The charge amounts of the first and second charging means are set so as to be smaller than the belt charge amount when passing through the first charging means and the belt charge amount of the supply-side endless belt. The inkjet recording apparatus according to claim 11.

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